class Solution{
public:
    bool isSameTree(TreeNode* p, TreeNode* q)
    {
        if (p == nullptr && q !=  nullptr )
            return false;
        if (p != nullptr && q == nullptr)
            return false;
        if (!p && !q)
            return true;
        if (p->val != q->val)
            return false;
        return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);            
    }
};